1. Field of the Invention
The present invention relates generally to a multilayer capacitor having a structure in which a plurality of inner electrodes are arranged so as to be overlapped with each other, separated by a ceramic layer in a sintered body, and more particularly, to a multilayer capacitor which is superior in Q characteristics in a high frequency band.
2. Description of the Prior Art
As is well-known, a multilayer capacitor has a structure in which a plurality of inner electrodes are arranged so as to be overlapped with each other through a ceramic layer made of dielectric ceramics and are alternately led out to different side surfaces of the dielectric ceramics. A multilayer capacitor of this type which is high in Q value in a high frequency band is required.
In order to increase the Q value, the equivalent series resistance (ESR) must be lowered. Different structures have been heretofore proposed: a structure in which one inner electrode comprises two inner electrode portions overlapped with each other through a thin ceramic layer (that is, a double electrode structure), a structure in which the wall thickness of an inner electrode is made large, and the like.
In the above described structures such as the double electrode structure and the structure in which the wall thickness of an inner electrode is made large, however, the eddy-current loss is so great that the ESR-frequency characteristics in a high frequency band are not improved, although they do achieve a decrease in the value of the ESR in a case where a direct current is caused to flow. Therefore, as shown in FIG. 2, in a high frequency band, for example, from tens of megahertz to several gigahertz, the ESR is higher. More specifically, the improvement in Q characteristics in such a high frequency band is not satisfactory.